Subsea couplings normally comprise a female coupler and a male coupler. The couplers are usually self-sealing and for this purpose may include a respective poppet valve, disposed so that the poppets mutually engage when the male probe is inserted in the female receiver. It is necessary to provide radial sealing between the couplers and various forms of metal and elastomeric seals have been proposed for this purpose.
The make-up of a pair of couplers necessarily occurs under water and many proposed design of coupling suffer from their susceptibility to high makeup forces and/or the entrapment of hydraulic fluid as the couplers are made up.
One known form of seal is a ‘C-seal’, which denotes an annular seal with a C-section. Such a seal has usually been made of metal but it may be composed of a hard material such as ‘PEEK’. Such a seal may be used as the primary radial seal between the couplers, and preferably used in conjunction with a secondary seal, providing a radial seal at a location spaced axially from the primary seal. The secondary seal may be a simple O-ring or a U-shaped elastomeric seal or an elastomeric or plastic ‘cartridge’ seal, comprising an O-ring with an encircling retaining ring of plastic or metal.
It is the general object of the invention to provide an improved subsea coupling.